According to the Santa Clara County District Attorney's Office, Lazarus Reavallez, now 18, was sentenced today for his role in the July 5, 2010, arson.
His co-defendant, Kliefert Guiang, also 18, remains in custody and is set to appear in court on June 19, according to the district attorney's office.
Reavallez and Guiang were 16 years old at the time of the fire, which destroyed 16 classrooms, the school's library and administrative offices.
The defendants allegedly set two fires on separate sides of the 1,000-student school -- using paper found in a recycling bin, cardboard and a cigarette lighter -- and fled.
Prosecutors say both defendants admitted starting the fire.
The two 18-year-olds were charged as adults for aggravated arson, a felony that carries a prison term of 10 years to life.
Reavallez pleaded guilty to a reduced felony charge, arson of a structure, which an enhancement adding four years to the term for causing damage in excess of $3.5 million, according to the district attorney's office.
"The defendants threatened the safety of the community, the well-being of the students and the people who live near Trace Elementary," prosecutor Alaleh Kianerci said today. "However, this fire devastated the students and teachers whose classrooms were destroyed."
The school was able to open in time for the following school year thanks to portable classrooms, and a newly rebuilt school is expected to be ready for the start of the 2012-2013 school year.